Proximate cause is a deliberate or careless act which causes someone else's injuries, pain, or damages.

What is Proximate Cause?

It is an action that brought about a result which is sufficient to be held accountable in court. For instance, in a personal injury case, the injured person has to show his injury was brought by the defendant's negligence or actions. The courts have to establish proximate cause for each case because not everything can be held liable for the injury.

The court asks two questions to decide whether or not the defendant directly contributed to the plaintiff's injuries:

  • Were the defendant's acts the cause in fact of the plaintiff's injuries?
  • Were the defendant's acts the proximate cause or legal cause of the plaintiff's injuries?

It's important to determine proximate cause because not everyone who causes an injury is legally liable. A real-life example took place in a 1910 case in the United Kingdom, where a man put poison in a glass of milk with the intent to kill his mother. His mother drank some milk and went to bed, to never wake up. The coroner determined she died of a heart attack and not the poison.

The actual poisoning was not the proximate cause of her death and her son could not be held criminally liable for her death. His mother would have died "but for" her son's poisoning the milk, as it was the heart attack which caused her death.

Another consideration the courts take is the foreseeability of harm. Even if it was considered an accident, a party can be held liable if the injury was foreseeable. If the person could have foreseen harmful consequences and taken action to deter this, then there is foreseeability.

Actual vs Proximate Cause

In order to prove negligence in court, the plaintiff has to prove the defendant's violation of duty was the actual and proximate cause of the injuries, including duty, breach of duty, and damages.

Actual cause, also called cause in fact, is simple to understand.

  • If a bus strikes a car, the bus driver's actions caused the accident.

Proximate cause has to be determined by the law as the primary cause of injury. The injury is the direct result of the proximate cause without which the injury would not exist.

  • It's an action that resulted in foreseeable consequences without anyone intervening.  

The But For Test

There are states who follow the "but for" test to determine proximate cause. The test considers whether the injury would not have occurred but for the defendant's action or carelessness. 

  • A drunk driver weaves through traffic and hits a pedestrian causing serious injuries. The accident would not have happened but for the driver's intoxication. Given his drunk driving actions, it is foreseeable that he could cause injuries to someone.

The Substantial Factor Test

Other states follow the substantial factor test to conclude proximate cause. If the defendant's act was a substantial factor in the injury, then he will be held liable for the injuries, unless he has a good defense to rebut the claims. A substantial factor contributes materially to the injury; the actions continue until the moment of injury.

  • A distracted driver crashes into a truck carrying explosives causing the explosives to explode and kill the truck driver. The distractive driving is the substantial factor in the accident and these actions continue until the explosion.


Causation is when one variable affects the other and at times the first variable can cause the second one to exist. In legal cases, causation is investigated to determine whether a defendant's actions or lack thereof caused someone else harm. 

There are two kinds of causation in criminal cases:

  • Factual causation uses the but for test to determine causation. It requires one question to determine causation: But for the defendants' actions would the injury occur?

Sometimes factual causation is not enough for the plaintiff to win a case, and legal causation is also brought into consideration.

  • Legal causation is when the plaintiff has to prove that his injury was directly caused by the defendant's actions. This extra consideration is taken because proving factual causation can be complex.

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